Plural stage miller with rotary impactors and rotary screens



March 21, 1950 F. 5. 5mm 2,501,622

PLURAL STAGE MILLER WITH ROTARY IMPACTORS AND ROTARY SCREENS Filed Sept. 7, 1944 3 Sheets-Sheet 1 j I INVENTOF Fran/villi 15'. Smith March 21, 1950 F. 5. SMITH PLURAL STAGE mum mm ROTARY mPAc'roRs mm ROTARY scams 3 Sheets-Sheet 2 Filed Sept. 7, 1944 0 M Ms Tm Z k m .Y. 8 M

March 21, 1950 F. 5. SMITH 2,

, PLURAL STAGE MILLER WI'H-I ROTARY IMPACTORS AND ROTARY SCREENS 3 Shets-Sheet 3 Filed Sept. '7, 1944 Patented Mar. 21, 1950 OFFICE PLURAL STAGE MILLER WITH ROTARY IIHPACTORS AND ROTARY SCREENS Franklin S. Smith, Hamden, Conn.

Application September 7, 1944, Serial No. 553,017

Claims. (Cl. 241-85) This invention relates to milling, and more partlcularly to a milling machine in which the product being milled is fed in an annular stream into the path of a plurality of impactors which mill the grain, after which it is classified according to size.

One of the objects of the present invention is to provide a thoroughly practical, efllcient and economical apparatus for milling grain or a like product. Another object is to provide appara tus of the above character which is simple in construction and capable of continuously milling a flowing stream of grain or the like.

Another object is to provide a construction of the above character in which particles of grain flow downwardly in a thin annular stream direct- 1y into the path of a series of impactors moving transversely to the direction of flow of the stream, thus insuring that each grain particle will be struck with a maximum of force by an impactor. Another object is to provide apparatus of the above character wherein the flowing stream of the product is directed into the paths of a plurality of revolving impactors in such a manner that the product is disintegrated with a relatively low power expenditure. Another object is to provide a method of milling which may be practiced continuously and economically in a minimum amount of space with a small outlay of power and labor. Other objects will in part be obvious and in part pointed out hereinafter.

The invention accordingly consists in the features of construction, combinations of elements, arrangements of parts. all as will be illustratively described herein and the scope of the application of which will be indicated in the following claims.

The many objects and advantages of the present invention may best be appreciated by reference to the accompanying drawings which illustrate one of the many possible embodiments of the invention and wherein:

Figure l is a vertical section of the milling apparatus with certain parts shown in elevation;

Figure 2 is a top plan view of the milling apparatus with part of the casing broken away to show certain details of the construction of the upper milling element:

Figure 3 is a fragmentary view of a portion of one of the milling elements showing the arrangement or the impaotors;

Figure 4 is a perspective view of an impactor;

Figure 5 is a view of another type of impactors;

Figure 6 is a horizontal section taken on the line H of Figure 1; and

Figure 7 is a vertical section taken on the line 1-4 of Figure 6.

Similar reference characters refer to similar parts throughout the several views of the drawings.

Referring particularly to Figure l 01' the drawings, housing III envelops an electric motor having a vertical shaft it upon the upper and lower extensions of which are mounted treatment rotors I6 and I8. As is best shown in Figures 6 and 7, motor I2 is totally enclosed by a motor casing and is supported within an outer motor casing I 25 spaced from the casing of motor I2 by means of conduits 2| and 24. An annular space I2! is formed around the casing of motor I2 by mean: of a band I26 which is connected to the casin of motor I2. Conduits 2| and 24 are connected to band I25 and open into space I21. Conoidal fans I3I and I32 mounted on motor shaft I4 draw air through ports I29 and I30 and drive it downwardly outside of band I26 into the space I28 between band I25 and outer casing I25 into exhaust conduits 22 and 23. Thus, air is circulated between the motor casing and outer casing I25 to cool the motor and dissipate heat resulting from milling.

The outer end of each of conduits 2|, 22, 23 and 24 rests in a cylindrical bracket I02 welded in an opening in the side wall in casing I0. As shown best at the right of Figure 1, each of the brackets I02 is partally cut away on its upper side within the casing so that the entire assembly, including motor I2, rotors I6 and I8. with screens 56 and I4, and hopper I0, may be lowered from above and the conduits move to the position shown wherein they rest upon the respective brackets. Removably held in each bracket I02 by four stud bolts I03 is a clamping ring I04, the extreme end of which carries a rubber sealing ring I06 and clamps the sealing ring against the end of the conduit. Thus after the rotor assembly is properly positioned the four clamping rings are clamped in place and the cooling air system of the motor I2 is thus sealed from housing I0.

Rotor I6 has a tapered axial bore into which the correspondingly tapered portion 28 of shaft I4 is held by a washer 32 and a nut 24 on the threaded end 36 of the shaft. A key 30 in suitable keyways prevents relative rotation between the shaft and the rotor. The outer portion of rotor It has a irusto-conical surface 21 and carries a plurality of impactors 30. These impactors are posltioned in staggered relationship (see also Figure 3) in two overlapping annular rows about the frusto-conical surface 31. Each impactor 28 is mounted in a suitable hole in rotor I6, and has screw-rods 58.

a base portion 48 (see also Figure 4) snugly fitting the hole and having a shoulder 42: four impactingbladm 44 project from base portion 40 beyond surface 3'! into the treatment zone 39.

Blades 44 are spaced apart with slots 49 between them so that the impactor presents four a leading impacting surfaces 48 separated by the slots 49. Thus, the impactor has a relatively large total impacting surface and yet the product is not deflected as the impactor moves through thegtreatment zone as might occur if the slots 49 were not provided. Each blade 44 is triangular intransverse cross-section with the base of the triangle at the impacting surface 48. Thus, each slot 49 is tapered with its narrow edge leading so that any particle of product which is small enough to enter the slot will readily pass through the slot. The air resistance and product deflection are considerably reduced by this structure.

Referring again to the upper portion of Figure 1, surrounding the treatment zone 39 and form:

ing an outer wall therefor is a frusto-conical screen or sieve 56 which is parallel to surface 31 and is supported at its lower edge by a plurality of Each screw-rod 58 extends through a bore in a perhipheral flange portion 51 oi the rotor frame ii, and near its head the screw-rod is threaded into the bore. The extreme end of each screw-rod is received in a recess Bil at the bottom of screen 58. Screen 56 is provided with a large number of small tapered slits or holes 64 which are long and narrow in crosssection-and extend radially with theirsmall ends open to the treatment zone. At the bottom of the inside of screen 56 is an annular product outlet 58 between the screen and the periphery of flange portion 51. a

The product to be treated. such as grain in either whole or broken condition, flows into the top of casing it from a conduit 50 through an annular passageway 6| formed by a stationary conical deflector 53 and a frusto-conical conduit extension 52. Deflector 53 and extension 52 are rigidly mounted on the top of casing ID by a plurality of stud bolts 55 threaded into sleeve extensions integral with deflector 53. The lower edges of deflector 53 and extension 52 are positioned in an inlet passageway 54 to the top of the treatment zone between the upper edge of screen 56 and the rotor frame ll. of extension 52 and deflector 53 are in closely spaced relationship with respect to each other so that the product to be milled enters the treat ment zone in a. relatively thin annular stream. The outer surface of deflector 53, which is of frusto-conical shape, is substantially aligned with respect to the outer surface of the rotor on which the impactors are mounted. The impactors are mounted at substantially right angles to the surface of the rotor on which they are mounted. Thus, the annular stream of the product flows from passageway into the top of the treatment zone where it is impacted by the various impactors 3B. The impacting action causes a partial disintegration of the grain and the centrifugal forces resulting from rotation are of sufficient magnitude to cause the product to tend to slide or flow downwardLv along the inner surface of screen 56. Holes 54 are of a size at their inher ends to permit the entry of any product particles which are of the size desired in the product; thus the product particles of the desired size are separated from the stream of the product shortly after they are formed. Furthermore. the outward taper in holes 64 insures that any par- The lower ends tlcle which is small enough to enter a hole wiii pass through the hole into the annular space 6i outside of the rotor. These particles of the prodnot fall and pass from the casing in a manner explained more fully below. The large or oversize particles of the product flow downwardly along the screen and pass from the rotor through the outlet 59.

The product from outlet 59 falls into an intermediate hopper 10 which is in two parts held together by set screws and the product is directed to the top of the lower rotor It. The lower endof hopper iii cooperates with a flange 80 on the casing of motor 12 to form an annular passageway 8i similar to the inlet passageway 54 at the top of rotor I 6. Rotor It has a rotor frame 83 which differs from rotor frame If only in that the central portion is inverted. the product treatlng portions of the two rotors being identical in structure and operation. Accordingly, rotor frame 83 has a tapered bore fitting a correspondingly tapered portion of shaft l4 and the rotor is keyed to the shaft and held in place by a nut 34 and a washer 32.

At the periphery of the rotor a plurality of impactors 12, identical with impactors 38, are mounted on a frusto-conical surface 13 with impacting blades positioned in an annular treatment zone 16. A screen 14, identical with screen I56, having tapered slits or holes 18 therein is mounted by a plurality of screw-rods 58 on the bottom of the rotor frame 83. The product moving downwardly through the treatment zone is impacted in the manner described above so that part or all of the product is reduced in size. The product particles which are sufficiently small pass through the screen into the surrounding space 85 and join the stream of the product falling from space 6|. These fine particles fall into a hopper 68 which directs them to a conduit 68. The oversize particles slide down along the inner surface of screen 14 under the influence of gravity and centrifugal forces and pass through an outlet 8? into a hopper 88. From the hopper 88 these oversize particles are directed to an outlet conduit 98 which passes through the side of hopper 66.

Hopper 8B is supported at four places around its upper edge in a manner best shown in Figure 2. Accordingly, at each point of support an arcuate spacer bracket 92 is welded to the inner surface of the casing and at the point of contact with hopper 88 it has a surface 83 which is machined to the contour of the adjacent surface of hopper 88. Threaded into the casing wall and extending through the spacer bracket into a hole 94 in the hopper is a screw-rod 95. During assembly the hopper is properly positioned between the spacer brackets and the screw-rods are then inserted. Thus, the hopper is accurately held in place and the proper clearance between the upper edge of the hopper and the lowe'r edge of rotor I8 is insured. The entire machine may be supported from below on a plurality of legs or from above by a frame construction. The electrical connection to motor I! is provided by wires, not shown, extending through one of the supporting conduits 2 i-24.

In the embodiment of Figure 5 the impactor I38 has its blades I44 positioned in staggered relationship; thus, their impacting surfaces I48 are offset one from another. Under some conditions of operation this type of impactor is substituted for the impactors 38 so as to give a more severe impacting action. Furthermore, the screens 56 and 14 may he changed in order to make them suitable for the particular product being milled.

From the above description it is apparent that the present invention provides an unusually efficient and practical apparatus for disintegrating a product to be, milled by impact. The flow of material through the apparatus is predominantly vertical thus permitting the use of gravity feed and providing uniform distribution of the product. This, in turn, gives a product of improved uniformity. With the structure illustrated, the product is fed to the impactors in a direction substantially parallel to the frusto-conical surface of the milling element and perpendicular to the direction of movement of the impactors. This perpendicular feed results in a highly efiiclent oblique impacting action and one in which the degree of disintegration may be more easily controlled. As the product leaves the impactor it has both a downward and an outward component of motion which increases the eificien'cy of the screens 56 and H. in segregating the fine and oversize particles. With any particular product being treated, the angle of the inside surfaces of screens 56 and I4 with respect to the axis is such that the product will slide or flow along the surface. Thus, the surface is at an angle greater than the angle of repose of the particular product. The apparatus is unusually compact and is capable of processing a large volume of the product in a continuous manner and at a rapid rate. The capacity of the air fans in motor I2 is greater than that necessary for merely cooling the motor so that an excess amount of air is circulated with the result that heat produced within casing in by the impacting and rotating action of the rotors is removed from the casing. Thus. the temperature of the product passing through the machine is not raised appreciably.

It is to be understood that the foregoing description is illustrative only and that many changes might be made without departing from the spirit of the invention. For example, although two milling elements are shown in the drawings it is evident that the milling process may be carried out in any desired number of stages. The number, shape and arrangement of the impacting blades 44 as well as the number, shape and arrangement of impactors may similarly be varied. Other variations within the scope of the invention will be apparent to those skilled in the art.

It will thus be seen that the several objects hereinabove referred to have been successfully and practically accomplished.

As many possible embodiments may be made of the mechanical features of the above invention all without departing from the scope of the invention it is to be understood that all matters hereinbefore set forth and shown in the accompanying drawings are to be interpreted as illustrative and not in a limiting sense.

I claim 1. In apparatus for milling or the like. the combination of. a casing having an annular inlet opening at its top and a pair of concentricalhr positioned hopper members at its bottom with separate product outlets from the hopper members. a motor having a vertical shaft and mounted within said casing and having air-circulating means which draws air into said casing to cool the motor and which discharges the warm air from the casing, a first rotor mounted upon the upper end of the motor shaft and having an anoLiiZ nuiar treatment zone positioned to receive the product from said inlet opening, said rotor comprising means to impact the individual particles of the product as the product enters said treatment zone under the influence of gravity and means to separate the particles of the product in accordance with the size. a second rotor mounted on the lower end of the motor shaft and having product impacting and separating means. means to receive the larger sized particles from said first rotor and deliver them to said second rotor, and means to deliver the separate streams of the product to the respective hopper members.

2.1m apparatus for milling a bulk product composed of individual solid particles. the combination of, a rotor frame having a peripheral portion with a substantially frusto-conical surface, a sieve rigidly mounted on said frame in spaced relationship with respect to said frustoconical surface, said sieve forming with said frusto-conical surface an annular treatment zone through which the product passes, and a plurality of impactors mounted on said rotor frame in staggered relationship in two overlapping annular rows concentric with the axis of rotation 'with the individual impactors extending transversely of said treatment zone with leading surfaces which impact the individual particles of the product passing through said treatment zone.

3. In apparatus for milling a flowable bulk product composed of individual solid particles, the combination of: a rotor comprising, a rotor frame having an annular peripheral portion the outer surface of which forms the inner wall of a treatment zone, a plurality of impactors mounted in spaced relationship around said peripheral portion and projecting from said outer surface through said treatment zone with the individual impactors having leading impacting surfaces which impact the individual particles of the product passing through the treatment zone. and a rotating separating screen surrounding said treatment zone and forming the outer wall thereof, said screen having an inner annular surface which is a frustum of a cone which surface slants away from the axis of rotation at an angle which is sufficient to cause the product to flow along the surface after being impacted by said impactors whereby the larger particles move along the inner surface of the screen whereas the smaller particles pass through the screen; and an annular chute having an annular outlet positioned adjacent said treatment zone to project a free-falling annular stream of the product into the path of the impactors.

4. In apparatus for milling a ilowable bulk product composed of individual solid parts, the combination of a casing providing a vertical passageway; a plurality of treating rotors mounted upon a common vertical axis in said passageway, each of which rotors is formed by. a rotor frame, an annular row of impactors carried by said rotor frame, and a frusto-conical separating screen carried by said rotor frame and extending downwardly and outwardly from the row of impactors, whereb the product is subjected to the impacting action by the impactors and then flows downwardly along the inner surface of said screen so that the particles of the product of larger size are directed from the bottom edge of the screen in an annular outlet stream and the smaller particles pass through the screen; chute means having an annular outlet to direct a free-falling inlet stream of the product to be treated into the path of the impactors 0f the upper rotor; and means 7 to receive the annular outlet stream of the prodnot from the bottom of the screen of the top rotor and to pass said annular outlet stream downwardly due to the action of gravity and also toward the axis of rotation.

5. In apparatus for milling a bulk product, in combination, a rotor including a treatment zone for the product being milled. said treatment zone being contained entirely within said rotor. said rotor including a solid inner wall and a screen forming an outer wall, said screen being of frustoconical shape having its vertex positioned above it on the axis of said rotor, the angle of said screen to said axis being greater than the angle of repose of the product being milled, means for driving said rotor, a plurality of impactors rigidly mounted on said rotor, means formin an annular inlet for the product being milled having the same axis as said rotor, said annular inlet being positioned directly above said impactors so that the product being milled flows from said annular inlet directly into the path of said impactors and is struck by said impactors before it engages any other part of said rotor, casing means surrounding said screen for collecting the milled productspassing through said screen, and easing means operatively associated with the flow of the prodnot passing downwardly off the lower inner edge of said screen for collecting the products which do not pass through said screen.

6. In apparatus as described in claim wherein the annular inlet is the mouth of a chute including two concentric frusto-conicall shaped members rigidly mounted in closely spaced relationship, said inner frusto-conically shaped member being substantially aligned with the surface of the rotor on which the impactors are mounted. the impactors being mounted at substantially right angles to the surface on which they are mounted. said frusto-conical members causing the product being milled to flow in a relatively thin annular stream into the path of said impactors at substantially right angles to the direction of movement of said impactors,

7. In apparatus for milling or the like, the combination of, a casing having an annular inlet opening at its top and a pair of substantially concentric hopper members at its bottom with separate product outlets from the hopper members, a totally enclosed motor mounted within an outer motor casing and havin a vertical shaft, said motor and said outer motor casing being enclosed within said flrst-mentloned casing, air circulating means which draws air into said outer motor casing and discharges it therefrom to cool the motor and to dissipate heat resulting from milling, a rotor mounted upon the upper end of the motor shaft and having an annular treatment zone positioned to receive the product from said inlet opening, impactors mounted on said rotor to impact the individual particles of the product as the product enters the treatment zone, said annular inlet being stationary and being positioned directly above said impactors so that the product being milled flows from said annular inlet directly into the path of said impactors and is struck by said impactors before it engages any other part of said rotor, and means in the treatment zone to separate the particles of the product in accordance with size.

8. In apparatus for milling a bulk product composed of individual solid particles. the combination of. a rotor frame having a solid inner wall, a screen of frusto-conical shape having a larger base than top. said screen being rigidly mounted on said frame in spaced relationship with respect to said solid inner wall. said screen forming with said solid inner wall an annular treatment zone through which the product passes, means forming an annular inlet for the product being mined. and a plurality of impactors mounted on said rotor frame directly beneath said annular inlet in staggered relationship in two overlapping annular rows concentric with the axis of rotation with the individual impactors extending substantially completely across said treatment zone with leading surfaces which impact the individual particles of the product passing through said treatment zone, the product being milled flowing directly into the path of said impactors and being struck by said impactors before it engages any other part of said rotor.

9. In apparatus for milling a fiowable bull: product composed of individual solid particles. the combination of, a rotor comprising a rotor frame having an annular peripheral portion the outer surface mounted in spaced relationship around said peripheral portion and projecting from said outer surface through said treatment zone with the individual impactors having leading impacting surfaces which impact the individual particles of the product passing through the treatment zone,

said impactors whereby the larger particles move along the inner surface of the screen whereas the smaller particles pass through the screen, an annular chute having an annular outlet positioned adjacent said treatment zone to project a freenot pass through the screen. 10. In apparatus for milling a fiowable bulk passageway. a plurality of treating rotors mounted upon a common vertical axis in said passageway, each of which rotors is formed by a rotor frame, an annular row of by said rotor frame, and a frusto-conical separating screen carried by said rotor frame and extending downwardly and outwardly from the row of impactors, whereby the product is subjected to the impacting action by the impactors and then flows downwardly along the inner surface of said screen so that the particles of the product of larger size are directed from the bottom inner edge of the screen in an annular outlet stream and the smaller particles passed through the screen. chute means having an annular outlet to direct a relatively thin annular free-failing inlet stream of the product to be 9 treated directly into the path of the impactors oi the upper rotor, means to receive the annular outlet streamof the product from the bottom of the inside edge of the screen of the top rotor and to pass said annular outlet stream downwardly due to the action of gravity, means forming an annular outlet in said last-mentioned means to direct the product flowing therethrough directly into the path of the impactors of the rotor positioned beneath the upper rotor, means to collect the annular stream of the product flowing downwardly oi! oi the inside edge of the screen of said second rotor. and means to collect the products passing outwardly through said rotor screens.

FRANKLIN 8. SMITH.

REFERENCES CITED The following references are of record in the Number Number iile of this patent: 90

UNITED STATES PATENTS Number Name Date 291,191 Ittner Jan. 1, 1884 794,785 Cox July 18, 1905 a 536,537

10 Name Date William Nov. 18, 1913 Bodey Jan. 23, 1917 McCoy Sept. 24, 1918 Plalsted Dec. 28, 1922 Mitchell Nov. 9, 1926 Agnew July 19, 1927 Bowman Nov. 29, 1927 Roebke Sept. 4, 1928 Crowe Feb. 5, 1929 Pettinos May '13, 1930 Grindle Mar. 31, 1931 Riley et a]. June 23, 1931 Symons Mar. 8, 193B Stearns Nov. 28, 1939 Mankofl Dec. 19, 1939 Schwarz Dec. 23, 1941 Gateiy Sept. 22, 1942 Poese May 18, 1943 Rletz July 27, 1943 Harris Mar. 21, 1944 FOREIGN PATENTS Country Date Germany Oct. 24, 1931 

